The present invention relates to a method and device for detecting a fiber lap on a rotating machine component, as well as a fiber cutting machine which includes the device.
When treating and processing strandlike fibers, the latter advance over or through rotationally symmetric components, which may be used, for example, as rolls for drawing, as feed systems for advancing, as pressure rolls, drive rolls, or pressure rings in fiber cutting machines. As soon as fiber strands advance in contact with or in the vicinity of such rotating components, there basically arises the problem that so-called laps may develop. In such cases, adhesive forces entrain the fiber strands on the circumference of the rotating component and wrap it around the component. Formations of such fiber laps must be rapidly detected to avoid long shutdown times or even destruction of the components.
To this end, methods and devices are known, wherein the circumferential surface of a rotating machine component is detected. In this case, one may basically differentiate between two variants. In a first variant, as is disclosed, for example, in EP 0 740 639 B1, the fiber lap is detected without being contacted. Specifically, the circumferential surface of the rotating component is sensed by means of a light source and an optical system. The light reflected from the fiber lap is used for identifying a fiber lap that has formed on the circumference of the component. However, optical methods and devices of this type are very susceptible to malfunction, since soiling of transmitters and receivers, as well as flying lint lead to frequent error detections.
In a second variant of the known methods and devices for detecting a fiber lap, a direct contact is produced between the fiber lap and a sensing element by mechanical scanning, as is disclosed, for example, in DE 101 12 679 A1 or JP 7133061. In both cases, a sensing element is positioned at a short distance from the surface of the rotating component. As soon as a fiber lap has formed on the circumference of the component, a direct contact of the fiber lap with the sensing element will release a measuring signal for detecting the fiber lap. Devices of this type, however, have the problem that the sensing element can get caught in the loops and irregularities of the fiber strands and that it can be entrained or be destroyed. In addition, joints, springs, and microswitches make the mechanical setup cost intensive as well as susceptible to wear.
It is therefore an object of the invention to provide a method and a device of the initially described type for detecting a fiber lap on a rotating machine component, which permits identifying fiber laps in a reliable and reproducible manner.
It is another object of the invention to provide a fiber cutting machine for a tow with a fiber lap detection device, which permits a rapid and reliable process intervention after detecting a fiber lap.
Another object of the invention is seen in providing a method and a device for detecting a fiber lap, as well as a fiber cutting machine with such a device for detecting a fiber lap, which permits detecting in a noncontacting manner laps that are produced by tows on rotating components.